Arc-reducing roll-contact for general electrical contact use



Sept. 5, 1950 A 2,521,521

C. W. JOHNSON ARC-REDUCING ROLL-CONTACT FOR GENERAL ELECTRICAL CONTACT USE Filed Dec. 29, 1948 fzveizo (Wm/212 m //M (4M cygiy I flfiya.

Patented Sept. 5, 1950 UNITED STATES PATENT OFFICE ARC-REDUCING ROLL-CONTACT FOR GEN- ERAL ELECTRICAL CONTACT USE Application December 29, 1948, Serial No. 67,836

Claims.

This invention relates to arc-reducing roll-contacts for general use in electrical contact applications, such as hand operated or mechanically operated switches particularly for industrial use, relays, circuit breakers, electric foot controls and the like, and constitutes an improvement upon the construction disclosed in my co-pending application Ser. No. 52,364, filed October 1, 1948, now Patent Number 2,485,532, Oct. 18, 1949.

In order that the principle of the invention may be readily understood, I have disclosed certain embodiments thereof in the accompanying drawing, wherein- Fig. 1 is a side elevation of a contact device representing one embodiment of the invention and showing the contact roll out of position with the non-rotary contact surface;

Fig. 2 is a similar view, partly broken away, representing the contact roll as having just engaged with the fiat insulating surface that precedes, touches and is flush with the flat contact surface;

Fig. 3 is a view similar to Figs. 1 and 2, but partly broken away, and representing the contact roll as having moved, by a wiping, rolling movement, into contact with the fiat contact surface;

Fig. 4 is a diagrammatic view representing in full lines the contact roll as having been moved into touching relation with the insulating surface and indicating in dotted lines a slight rolling advance of the contact roll along said flat insulating surface;

Fig. 5 is a diagrammatic view similar to Fig. 4, but representing the contact roll as in touching relation with both the insulating surface and the contact surface where their edges meet in touching relation;

Fig. 6 is a diagrammatic view similar to Figs. 4 and 5, but representing the contact roll as having moved with a wiping, rolling movement into contact with the contact surface, having left the said insulating surface;

Fig. 7 is a plan view of the construction shown in Fig. 1;

Fig. 8 is an end view of the construction shown in Fig. 1, looking from the left in said figure and partly broken away;

Fig. 9 is a side elevation, partially broken away, of a hand-operable or mechanism-operable switch embodying my invention, which switch is normally open; and v Fig. 10 is a similar view of a similar switch embodying my invention which, however, is nor- The purpose of my invention is to provide an arc-reducing roll-contact for general use in electrical contact applications which will give a positive make-and-break for practically unnumbered cycles, and the use whereof occasions only very mally closed. -.,,ao

2 faint sparking and that dependent upon the amperage.

In my said co-pending application Ser. No. 52,364, I disclosed a contact-making device wherein both of the contact members are formed as freely rotatable rolls mounted in parallelism, one or both of said rolls tending to turn as they contact or separate, whereby upon recontact a different contact area is presented by one or both of said rolls.

While the said device disclosed in my said copending application operates very satisfactorily, I have obtained even better results by the constructions herein disclosed, wherein one only of the two contact members is formed as a freely rotatable roll, the other contact member being formed as a flat surface which, in Figs. 1 to 9, is preceded by an insulating surface that is accurately flush with the said flat contact surface and is in edge-to-edge touching relation therewith, so that as the contact roll is moved in any suitable manner to make contact, it touches with a wiping, rolling movement first the flat insulating surface, and then moves with a continuation of the said wiping, rolling movement into contact with the said flat contact surface.

Moreover, the said flat contact surface and the said flat insulating surface positioned anterior thereto are together spring-pressed toward the path of movement of the said contact roll. In the embodiment of my invention shown in Fig. 10, the switch is normally closed, and hence the insulating surface, instead of being anterior, is posterior to the contact surface, but is accurately flush therewith, the contact roll moving from the contact surface onto the insulating surface to open the switch.

The provision of the fiat contact surface and the insulating surface flush with each other and in edge-to-edge contact reduces the amount of sparking to an absolute minimum.

Referring more particularly to the drawing, and first to the embodiment of the invention shown in Figs. 1 to 8, and particularly to Figs. 1, '7 and 8, it is to be noted that I have not therein shown all the parts of a relay or other contact device as in my said co-pending application, it being unnecessary to do so inasmuch as there are a great number of uses to which the invention may be applied, including, as already stated, switches that may be operated by hand or mechanically, particularly for industrial use, relays, circuit breakers, electrical foot controls and the like.

vI have, in Figs. 1, 7 and 8, indicated an arm or lever at I, it being pivoted at 2 upon a suitable base 3 and having pivotally connected thereto at 4 a link 5 pivotally connected at 6 to a rotary member I, so that upon rotation of said member 1 the contact roll 8 is moved to and fro to make-and-break contact with the other contact member.

The said contact roll 8 may be formed wholly of any suitable material such as bronze, but preferably I provide it with a silver or equivalent contact surface such as 9, of the character shown in my said co-pending application. Within the scope of my invention either of such constructions may be used. While the size of the roll 8 may be varied, it is desirably about five times larger than the ordinary relay contact, but this size may be varied substantially, without departing from the scope of my invention. A contact roll about one-quarter of an inch wide and about a half-inch in diameter gives excellent results when employing a current of about 110 volts, ten amperes. With a greater amperage the contact roll should .be greater in diameter and width.

Still referring to Figs. 1 to 8, the said contact roll 8 is mounted in any suitable manner as, for example, in a pair of parallel supporting members or brackets I 0, Figs. 1, 2 and 3, and it may be secured by bolts, as indicated at II, to the lever or member I. A wire I2 is indicated as electrically connected to the lever or member I which is, of course, of suitable conducting material, as are the brackets Ill. Insulation is preferably provided at I2 at the foot of the link 5.

Instead of constructing the other contact member as a contact roll, as in the construction shown in my said copending application, I have constructed the second contact member as a nonrotary flat member composed of the actual contact surface I3, which is formed of bronze, silver or any other suitable contact material, and an insulating surface I4 which, as best shown in Figs. 4, and 6, is perfectly flush with the contact surface I3 and is in actual touching edgeto-edge relation therewith, as indicated in all the Figures 1 to 6.

Still referring to Figs. 1 to 8, both the surfaces I3, I4 may be mounted in any suitable way upon a suitable support. In Figs. 1, 2 and 3 the contact surface I3 is represented as formed with or attached to a lever arm or member I5 of any suitable conducting material, and the insulating surface I4 is represented as secured by a bolt or screw I6 just above the contact surface I3, so that as described the two surfaces I3, I4 are exactly flush with each other and are in edge-to-edge touching relation. Therefore, as the contact roll 8 is moved downward, in the embodiment of the invention shown in Figs. 1 to 8, the surface of said roll 8 touches first the insulating surface I4, as shown in Fig. 4 and also in Fig. 2, and then immediately moves with a wiping, rolling contact onto the contact surface I3 until it reaches the position shown in Fig. 6, with a very minimum of sparking or even without any observable sparking.

The width of the contact surfaces I3, I4 should, for best results, be the same as the length or width of the contact roll 8 from end to end thereof, but this may be varied within the scope of my invention.

The lever arm or member I5 may be a single piece or it may, as indicated in Figs. 1, 2 and 3, be a short piece connected by a bolt or screw IT to a lower member I8 of suitable conducting material, which itself is pivoted at I9 upon any suitable support and to which a wire is connected, leading from any suitable source of electricity in a manner that need not be more particularly referred to. The member I8 may be 4 suitably insulated from the part whereon it is mounted.

The lever arm herein shown as composed of the two parts I5, I8 is spring actuated so that it tends to move toward the path of movement of the contact roll 8. For this purpose I have represented a slight coil spring 2| secured at one end to the lever member I8 and at its other end to a stationary support 22. This constitutes a pull spring. I may employ instead a push spring located at the back of the lever arm or member I8 and of equivalent strength to the pull spring 2I or I may instead form the lever member I8 as a spring of phosphor bronze or the like so that it has a tendency to move slightly toward the path of movement of the contact roll 8. Such spring of phosphor bronze or the like may be formed as a straight or fiat spring member, or it may be of general hairpin or loop form to provide the requisite spring support.

It is important to support the contact member I3 at just the right angle from the path of movement of the contact roll 8.

Still referring to the embodiment of the invention shown in Figs. 1 to 8, and particularly referring to the construction shown in Figs. 1, 2 and 3 wherein the contact roll 8 is pivoted upon a horizontal support, so as to be moved downwardly to mak the described contact, I have found by careful experimentation that the best results with this embodiment of my invention are achieved by supporting the member or lever I8 so that when it is in the position shown in Fig. 1, it is about or substantially ten degrees back of a truly vertical position or line. Then as the contact roll 8 moves downward into the position shown in Fig. 2 and then further downward into the position shown in Fig. 3, the said lever or member I8 yields slightly further backward awa from its initial position of substantially ten degrees back of a truly vertical position.

The insulating surface I4 may be formed of any suitable insulating material such as Bakelite or any other high insulating plastic.

The contact roll 8 turns slightly upon its axis as it makes and breaks contact, and therefore upon the next contact a different surface is presented for contact. Because of this fact, the contact roll 8 lasts indefinitely while making many hundreds of thousands of contacts. Any faint sparking that may occur is dependent upon the amperage and has been found to be exceedingly slight in practice.

It will be observed that as the contact roll 8 moves downwardly from the position shown in Fig. 1 to that shown in Fig. 2 and then to the position shown in Fig. 3, increased spring tension results because of the spring 2 I, or its equivalents as described, and the very accurate positioning of the lever member or arm I8 at about ten degrees back of a truly vertical line as described.

In Fig. 9 I have represented an embodiment of my invention wherein the device is a switch that is desirably entirely enclosed in a casing, such as 23, which may be formed of Bakelite or any other suitable insulating material and which has a removable top or cover 24 secured in place by screws 25 so that access may be readily had to the interior of the casing by removing the said top of cover 24. The contact roll, which is here also indicated by the numeral 8 and which is desirably provided with a silver or like contact surface, is supported by parallel brackets 26, Figs. 1 to 8,

upon the outer end of a suitable flat spring member 21 of suitable contact material, it being secured at 28 to a part 29 of the casing 23. Supported in contact, or substantially in contact, with the upper surface of the spring 21 is a plunger 30 that is supported and guided for vertical movement in the top or cover 24 of the casing. The upper end of the plunger 30 may be enlarged as shown at 31, and the said plunger 30 is adapted to be engaged either manually or by soine constantly or intermittently operating part of the mechanism with which the switch is used, so as to move the contact roll from engagement with the insulating surface 32 into engagement with the contact surface 33. The return movement of the plunger 30 is limited by a stop 3|. The said two surfaces 32, 33 are perfectly flush with each other and are in edge-to-edge touching position as described with respect to Figs. 1, 2 and 3. The said insulating and contact surfaces 32, 33 are supported in the described relation by a spring arm 34 of suitable conducting material which is itself secured by screws 35 to the inner face of the bottom wall of the casing 23. Suitable wires (not shown) are provided, as in Figs. 1 to 3, to a suitable source of current.

It will be observed that in Fig. 9 the contact roll 8 is normally in contact with the insulating surface 32 so that the switch is normally open. By depressing the plunger 30 either manually or mechanically at the desired times, the switch is closed because the contact roll moves with a rolling, wiping action onto the contact surface 33.

The construction shown in Fig. 10 is the same as that shown in Fig. 9, with the exception that the switch is normally closed, inasmuch as the contact surface 33 is at a higher elevation than the insulating surface 32, and the same reference numerals are employed. Therefore, downward movement of the plunger 30, by the application of manual pressure or by an operating mechanical part, opens the circuit by moving the contact roll 8 by a rolling, wiping movement onto the insulating surface 32 which, as in Figs. 1, 2, 3 and 9, is fiush with the contact surface 33 and is in edge-to-edge touching relation therewith.

Having thus described certain embodiments of my invention, it is to be understood that although specific terms are employed, they are used in a generic and descriptive sense and not for purposes of limitation, the scope of the invention being set forth in the following claims.

I claim:

1. A switch, relay, circuit breaker and the like, comprising two contact members, one of said contact members including a yielding arm mounted upon a support and adapted to be moved to-andfro upon its said support by the application of force thereto, from an upper position in which said yielding arm is out of contact with the second contact member, to a slightly lower position to make contact with the said second contact member, said yielding to-and-fro movable arm having at its outer free end a pivoted contact roll free to turn upon its pivot in either direction at all times, there being an insulation surface supported in close proximity to but extending slightly above said second contact member and closeto the downward path of movement of said contact 7 roll on said yielding arm, and spring means tend-- ing to move said insulation surface inward toward and to the path of movement of said contact roll toward said second contact member when the said yielding arm has pressure applied thereto for the purpose of the said second cont tact roll when s first with the sai with the said seco 2. A switch, relay, comprising tw members inclu moved upon its pivot by the thereto, from a posi zontal when it is ou member, to a slightly lower p tact with the having at its ou upon its pivot said other contact membe member inwardly toward the other member,

contact member having upon portion and an insulation portio making electrical contact with act member, so that said con- 0 moved downwardly, contacts (1 insulation surface nd contact member.

circuit breaker and. the like 0 contact members, one of said ding a pivoted arm adapted to be application of force tion slightly above the horit of contact with'the other osition to make contending to move said second vertical, said second its face a contact the pivot of the contact roll but sufficiently close to said surface so moved downwardly, then with the other 3. A switch, relay,

accordance with claim 2, but

tion portion upon the sai is above but fiush with the sa 4. A switch, relay, in accordance with cl tact portion is above said other contact member circuit insulation portion.

5. A switch, relay, comprising two contact po bers including a pivoted ar that said contact roll, when contacts first with one and of said portions.

circuit breaker or the like in wherein the insulad other contact member 'd contact portion.

breaker or the like aim 2, but wherein the conthe insulation portion upon but flush with the said circuit breaker and the like rtions, one of said memm adapted to be moved upon its pivot by the application of force thereto,

and the other 0 yieldingly suppor bers being so moun right angles to each 0 the inner free end proximity with eac ber carrying a roller a pivot and which roller is free upon its axis in either member being so suppor backward from a positi tion of the first mentione tending to move said second free end of said first having upon its face an insulated portion are flush with eac lation with each 0 plied to the first me portions.

f said contact members being ted at one end, said two memted that they are at about ther, each extending toward of the other and into very close h other, the said pivoted memt its end remote from its at all times to rotate direction, the said other ted that it extends slightly on normal to the posi- (1 member, spring means member toward the member, said second member that is nearer to said roller and a contact portion that h other and are in touching rether, so that when force is apntioned member the said roller moves along said insulation and contact CHESTER W. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 468,120 Thomson Feb. 2, 18922 576,369 Kritzer Feb. 2, 1891 1,214,309 Jillson Jan. 30. 1917 Hogan ans...

6...... May 1 .8

and then said pivoted arm ter end a contact roll free to turn in either direction at all times,

r being mounted in upright position slightly back from a vertical position, spring means 11 flush with each hing relation with each other, t member being of such length and insulation portions are izontal plane passing through 

